Prior to the present invention, teach tools such as mechanical contacts have been installed on the manipulative head of a robot, and the head has been moved by a programmer across master work pieces. By observing the teach tool and the physical contact thereof with master work pieces, a program was developed for teaching robots to follow a certain course and to execute laser work such as cutting or welding. The prior teach tools usually employ a telescopic plunger with an observable optimized work or indicator line such as a ring painted on the plunger so that a programmer can move the robot to selected stations to observe the work line while the plunger physically engages the point to be welded so that the work or weld points can be programmed to appropriately control the weld. If there is to be a linear or curved weld, the programmer will move the plunger from a starting point across the intended weld line until the terminal point is reached. The weld indicator line of the plunger will be observed during this time by the programmer to insure that the beam will be appropriately focused on the points to be welded. While these prior teach tool have allowed for improved laser weld for many components, difficulties have been encountered in precisely programming a welder to provide optimize welds. Most of these difficulties occur because the programmer is unable to precisely observe the work indicator line, position of the plunger and its exact point of physical or tip contact in teaching the laser unit to work at optimized points.
Furthermore, it was necessary to dismantle parts of the robot, such as the air knife, prior to attachment of the teaching plunger. The prior teach tool was particularly difficult to use in programming the laser unit where work parts are clamped together and the laser work had to be executed in openings within the clamps and other adjacent areas which are extremely difficult to observe. Additional difficulty arose when the welder had to be taught to weld work pieces having complex curvatures and surfaces to be welded. Generally, this involved averaging observed contact points along the curved workpieces to generally obtain an acceptable weld. Some of such welds were subsequently rejected and rework was required.
The present invention overcomes the difficulty of the prior art teach tool by providing a noncontact teaching tool and method incorporating a focused light visible pointer in which the programmer can readily observe and program at selected work points. The focused visible light simulates the position of the laser beam and allows the programmer to view darkened areas that are often encountered in areas such as in or near workpiece clamps and other obstructions. Additionally, the present invention allows the programmer to be assured that the light beam accurately simulates the laser beam by the inclusion of displacement sensor that incorporates a small battery powered laser within the teach tool. The laser beam generated by the sensor, invisible to the human eye, is mounted to a teaching pendant attached to the air knife whose height and position are determined by comparator circuitry and visible indicator lights so that the programmer knows by visible observation of the indicator lights whether the laser is positioned by the robot at a proper focal length for the optimized laser working of a plurality of substantially identical work pieces.
It is a feature, object and advantage of this invention to provide a new and improved noncontact teach tool and teaching method for programming a robot so that a laser beam work device carried by the robot using the program performs work with optimized precision on a series of work pieces as taught by the teach tool.
It is a feature, object and advantage of this invention to provide a new and improved teach tool and method for programming a robot so that a programmer can determine with optimized precision the points at which laser beam work is to be performed on a master workpiece and to develop a program that can be used to effect laser beam work on a series of workpieces which are like the master workpiece.
Another feature, object and advantage of this invention is to provide a new and improved portable teach tool for teaching a robot to follow a predetermined path and execute laser beam work at predetermined points or lines which incorporates a pendant type housing attached to the manipulative head of a robot in which there is a visible light pointer that can be energized and focused at a point that simulates the point at which the working laser beam is to be focused so that the programmer can program the work points for the robot and further in which there is a battery powered laser used to produce a displacement measuring laser beam that coincides with the visible light point to measure and to optimize programmer the determination of the precise points at which the working laser is to be focused.
A feature, object and advantage is to provide an new and improved noncontact teaching tool for a laser beam robot welder to make repetitive welds of a plurality of work pieces in an optimized fashion to improve welds and welder efficiency.
Another feature, object and advantage of this invention is to provide a pendant type teach tool for a robotic laser beam welder in which a focused incandescent lamp is employed to indicate the weld points of a focused laser beam.
Another feature, object and advantage of this invention is to provide a new and improved quick change gas tube for an air knife assembly of a robotic laser beam device so inert gas can be delivered to the working point of the laser beam.
These and other features, objects and advantages of this invention will become more apparent from the following detailed description and drawings in which: